This is a Phase II, randomized, open-label, multi-center study in advanced (Stage IVA and IVB subjects per the International Association for the Study of Lung Cancer (IASLC) 2009 Lung cancer staging schema) non-squamous NSCLC subjects comparing pazopanib relative to pemetrexed in the maintenance setting. Subjects should have completed 4-6 cycles of induction therapy with carboplatin + pemetrexed or cisplatin + pemetrexed and have had Stable Disease (SD), Partial Response (PR) or Complete Response (CR) as the best response to be enrolled into the study. The primary objective is to estimate the hazard ratio of progression free survival (PFS) in advanced NSCLC subjects given maintenance therapy of pazopanib (Arm A) relative to pemetrexed (Arm B). The secondary objectives are: overall survival, response rates, safety and tolerability. A total of approximately 200 subjects will be enrolled and randomized in a 1:1 ratio. Safety and efficacy assessments will be regularly performed on all subjects.